Process for producing catalyst supports or catalyst systems having open pores

Abstract

A process for producing ceramic, ceramic-metal or metal catalyst supports or catalysts with open, interconnecting pores. The process forming a dense agglomeration of spherical, cylindrical or similar bodies of generally uniform size. These bodies are connected together at their mutual contact points, thereby producing a framework corresponding generally to the macropores and pore interconnections of the finished material in terms of size and arrangement. The framework is then filled with a suspension containing as solid components the catalyst support material and/or the catalyst material. The suspension can also contain a binding agent. The framework is subsequently dissolved away after at least the partial hardening of the cast mass without destroying the structure produced during hardening.

What is claimed is: 
     
       1. A process for producing a solid ceramic catalyst, a solid ceramic-metal catalyst, a solid metal catalyst, a solid ceramic catalytic support, a solid ceramic-metal catalytic support or a solid metal catalytic support, having open interconnecting pores using a framework in the production process which comprises (a) forming a dense agglomeration of spherical bodies of approximately uniform size, said spherical bodies being insoluble bodies having a low melting point or bodies which are soluble in a solvent, and said spherical bodies being capable of being dissolved, evaporated or burned to remove the framework, and (b) connecting together these bodies at their mutual contact points, the initial mutual points of contact of the spherical bodies being enlarged by attachment to each other by means of (i) dissolution, the bodies being connected together by pouring a solvent, which gradually dissolves the material of the spherical bodies, into said dense agglomeration of spherical bodies and by removing said solvent after a short reaction period leaving a film of said solvent on the bodies which forms a fluid meniscus on the contact points of the bodies, (ii) gluing or (iii) sintering into larger areas or surfaces of contact, whereby a framework corresponding in size and arrangement generally to the macropores and pore interconnections of said catalyst metal, said catalyst ceramic, said catalyst ceramic-metal, said catalytic metal support, catalytic ceramic support or said catalytic ceramic-metal support is produced, (c) filling the framework with a suspension containing, as the solid component, said catalyst metal or said catalyst ceramic or said catalyst ceramic-metal or said catalytic support metal or said catalytic support ceramic or said catalytic support ceramic-metal, said framework being prepared from spherical bodies capable of being evaporated or burned substantially below the sintering temperature of said solid component of said suspension used as the framework material, (d) partially or completely hardening said suspension by applying sufficient heat to effect said partial or complete hardening, (e) dissolving away or removing the framework without destroying the structure produced during such partial or complete hardening, said removal of the framework being achieved by applying sufficient heat to evaporate or burn said framework, and (f) if there has been only partial hardening of the cast mass, completely hardening said suspension by applying sufficient heat to effect said complete hardening. 
     
     
       2. A process according to claim 1 wherein the suspension also contains a solid binding agent. 
     
     
       3. A process as described in claim 2 wherein said solid binding agent is a binding clay. 
     
     
       4. A process according to claim 1 wherein said solvent is an acetone and water mixture. 
     
     
       5. A process according to claim 1 wherein said solvent is removed by evaporation via a heating step. 
     
     
       6. A process as described in claim 1 wherein said ceramic catalytic support is Al 2  O 3 . 
     
     
       7. A process as described in claim 1 wherein said suspension contains added pulverant catalyst metal, a metal powder dross stabilized by a binding agent or a mixture thereof. 
     
     
       8. A process as described in claim 1 wherein the spherical bodies are connected together by being moistened with an adhesive having a low viscosity and being glued together thereby at the contact points and wherein the spherical bodies are insoluble. 
     
     
       9. A process according to claim 1 wherein, to produce said framework, said spherical bodies are sintered at their contact points by raising the temperature to just below their melting point, and wherein said spherical bodies have a low melting point. 
     
     
       10. A process according to claim 9 wherein said framework material is polystyrene. 
     
     
       11. A process according to claim 9 wherein a liquid-solid suspension of (i) a ceramic, (ii) a vitreous ceramic, (iii) a glass or (iv) a high temperature resistant material selected from the group consisting of an oxide, nitride, silicide or boride material, and a suitable binding additive, is used as said suspension, the microporosity of the resulting material being capable of being influenced by the sintering process. 
     
     
       12. A process according to claim 11 wherein metal acting as a catalyst is added to said suspension. 
     
     
       13. A process according to claim 11 wherein said suspension contains a catalytically active metal powder mixed with a suitable binding agent, the microporosity of the resulting material being capable of being influenced by the sintering conditions. 
     
     
       14. A process according to claim 11 wherein said catalyst support consists of a catalytically-inactive metal, ceramic or ceramic-metal and a metal catalyst is applied to said catalyst support, after the framework is removed by separation from the gaseous phase at gas pressures below approximately 1/100 psi. 
     
     
       15. A process according to claim 11 wherein the catalyst support consists of a catalytically inactive material metal, ceramic or ceramic-metal, and a metal catalyst is applied to said catalyst support, after the framework is removed by chemical reduction from the aqueous phase. 
     
     
       16. A process according to claim 11 wherein said catalyst support after the framework is removed, is saturated with the solution of a metal salt, and a metal catalyst is produced from said metal salt by reduction using hydrogen in the gaseous form.